Electrical flash lamp system



A. F. HENNINGER ELECTRICAL FLASH LAMP SYSTEM Filed Feb. 20, 1946 July 25, 1950 Patented July 25, 1950 UNITED STATES PATENT OFFICE 2,516,209 ELECTRICAL FLASH LAMIP SYSTEM Andrew F. Henninger, Chicago, 111. Application February 20, 1946, Serial No. 649,051

' 3 Claims.

My invention relates to an electrical flash lamp system for use in photography, and more particularly to a circuit arrangement that provides a visual indication showing whether or not the system is electrically conditioned for producing a luminous discharge in the flash lamp.

The flash lamp system with which my invention is used is normally of the portable, battery operated type. Low voltage D. (3'. power from the battery is applied to a vibrator device which supplies pulsating current to the primary of a step-up transformer. The high voltage output of the transformer secondary is rectified and applied to one or more storage condensers. The storage condensers, when fully charged, contain suflicient energy to produce a luminous discharge in the flash lamp, which discharge is synchronized with operation of the camera shutter.

One object of my invention is to provide a visual indication that shows the operator whether or not the storage condensers are sufliciently charged to produce the desired luminous discharge in the flash lamp. With such indication, the operator is enabled to avoid premature film exposure.

Another object is to provide a safety arrangement whereby the high voltage of the charged condensers may gradually leak away, thus avoiding some of the dangers inherent in using voltages of the order of 2,000 volts.'-

Others object and advantages of my invention will be apparent as the description proceeds, reference being had to the accompanying drawing which illustrates one form of the invention. It will be understood, of course, that in a practical, commercial application of the invention, the essential features are necessarily susceptible of changes in details and arrangements. The legal scope of the invention is to be measured by the claims hereinafter set forth.

As the flash lamp system to which my invention is applied utilizes the accumulation of energy over a relatively long period of time, with discharge of the accumulated energy in an extremely short space of time, I am able to utilize as an energy source, when portability is paramount, a single small storage cell I normally rated at 2.2 volts or two dry flashlight cells. One side of this battery is connected to an armature 2 carrying an armature contact 3, opposed by a stationary contact 4 which in turn is connected to the primary 5 of a step-up-transformer 6 having an iron core I, one end of which is positioned to move armature 2. The other pole of battery I is connected to the other end of primary 5 to complete the primary circuit. A switch 8 is positioned in the primary circuit to control current flow therein, and a by-pass condenser 9 of .25 mf. is bridged across battery I.

A secondary winding I0 is provided to complete the transformer structure and in the preferred circuit it normally is wound to provide a 1:70 voltage ratio. However, by placing a .5 mi. condenser I I across the primary 5 of the transformer, thereby tuning the primary circuit, and b coordinating the vibratory frequency of the armature, I am able to obtain from the battery I a secondary voltage of about 2,000 volts.

This secondary voltage is passed through a rectifier tube I2 connected to one end of secondary I0 and the D. C. pulses are stored in two 8 mid. condensers I4 in turn connected to the other end of secondary I0 by wire I5. Rectifier tube I2 may be, for example, an inert gas tube which has a high inverse voltage rating. A dry disc rectifier may also be used. The circuit is arranged so that condensers I4 charge up to full voltage in from 10-20 seconds, preferably in about 16 seconds.

Theenergy stored in condensers I4 is released through a relay I5 with contacts I6 connected to discharge the condensers I4 through a flash lamp I! provided with a reflector I8. This lamp is preferably of the gaseous conduction type known as the "Amglo lamp full described and claimed in U. S. Patents 2,281,579, 2,217,315, 2,219,923 and 2,273,520, also preferably with xenon gas filling, preferably at about 25 m. m. Hg pressure, as I have found that the actinic value of the lamp filled with zenon is high, appears white, is effective over wide ranges of film response and is suitable for natural color photography, does not adversely affect the eyes of those exposed to the flash or cause the nervous reaction usually following metallic combustion flashes of similar duration and intensity. The flash, due to the condenser discharge, takes only a few milli-seconds for completion, and this is readily synchronized with camera shutters so that the flash takes place while the shutter is open.

In order that standard synchronizers may be used, such as might already be installed on cameras for use with metal combustion bulbs, relay winding 20 is provided with a cord 2| terminating in a bayonet plug 22 of a size to fit standard synchronizers. As such synchronizers contain a battery, no connection to battery I IS needed. However, in order that the lamp Il may be flashed at will, a flash switch 24 is provided connecting battery with relay winding 20 through wire 25.

Because of the fact that I can obtain high voltage from transformer 6, even from a single battery cell, and because I charge the condensers I4 over a substantial time period, I am able to deliver through the lamp a substantial amount of power in the short flash, and thus obtain satisfactory actinic power even though only a single dry cell is used as the power source. Tests have shown that the lamp flashes delivered by lamp I! are in every way comparable for photographicpurposes to the single exposure combustion lamp commonly used for flash exposures of camera films.

In such a circuit as has been described, it is highly desirable that the operator at all times be able to know the charge conditions of-con an electrical discharge lamp, a condenser providing energyfor said lamp, an intermittent D. C.

densers M, and to that end I haveprovidedan indicator device preferably comprising a cold cathode glow lamp 2! of standard low currentlow voltage type, connected across condensers l4 through-a condenser- 28 of about :01 mm'f;,-

capable of withstanding the series voltage. I

may also prefer to by pass this condenser with a very high resistance: leak 29,-although I have found "that some --condensers have sufficient internal'leaka'ge to'operate to-give the desired indication without an external resistor.

The modeof 'operation desired and accomplished 'by the indicator device described, is that while condensers I 4 are charging; the D; C; pulses imposed on glowlamp '21 cause this lamp to flash intermittently. '1 However, as the voltage incondensers M approaches the supply voltage, flash source for impressing a charge on said condenser,

and means .for discharging said condenser through said lamp, the combination therewith of a gaseousdisc'harge glow tube connected across -said condenser in series with a capacity bridged by a resistance leak whereby said tube flashes as said condenser is charging and .glows steadily aftersaid condenser has reached full charge, the said resistance leak being-proper! tioned todischarge said condenser in a time .period in-minutes when the condenser charging time is in seconds,

3. In. an-electrical system having a condenser for providing energyto a load. and intermittent D. C. means for charging .said condenser, the

. combination therewith -'ot a gaseous discharge ing'ofthe glow-lamp ceases, and the light therein becomes continuous; due to leakage across condenser-.282; Thus full charge on'condensers' I4 can be determined;

The small leak across condenser '28 also acts as a safety factor in'case-the circuit is left with afull *chargeo'n condensers [4; as the leak across condenser 28 will discharge rcondensers I l-in.

from tento fifteen'minutes;

From the above description it is thoughtthat the construction-and advantages of'my invention will beflreadily apparent to those skilled in the art; Various --changes "zan'd'zmodifications may be made without'departing from thespiritor losing the advantages of the invention;

Having thus'describedmy invention, what I a Patentisr- 1. In an electrical flash l'amp system having Number Name Date 1,849,376 Morse Mar. 15,1932 1,922,984-- Soundy Aug.- 15, 1933 1,955,520 we Vawter ,Aprpl7, 1934 2,181,879 Edgerton; Dec-5, 1939- 2,196,-046 Willis'u Apr. 2, 1940" 72,290,264 Wuerfelv; July 21, 1942-- 2,341,541-' Grier Feb. 15, 1944 2,385,397- Blackburn Sept. 25,

glow tubeconnected. across said condenser, a

capacitance in'series with said glow. tube, and a resistance leak inparallel-with said capacitance whereby said tube "flashes as said condenser is charging and glows steadily-when said condenser has reached substantially. 'full charge. I

1 ANDREW F. -I-IENNINGER.

REFERENCES CITED following references are. of file of this patent: V

UNITED STATES PATENTS record in the 

